Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) systems have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of tissue stimulation has begun to expand to additional applications, such as angina pectoralis and incontinence. Deep Brain Stimulation (DBS) has also been applied therapeutically for well over a decade for the treatment of refractory chronic pain syndromes, and DBS has also recently been applied in additional areas, such as movement disorders and epilepsy. Further, in recent investigations, Peripheral Nerve Stimulation (PNS) systems have demonstrated efficacy in the treatment of chronic pain syndromes and incontinence, and a number of additional applications are currently under investigation. Furthermore, Functional Electrical Stimulation (FES) systems, such as the Freehand system by NeuroControl Corporation, Cleveland, Ohio, have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.
These implantable neurostimulation systems typically include one or more electrode carrying stimulation leads, which are implanted at the desired stimulation site, and a neurostimulator (e.g., an implantable pulse generator (IPG)) implanted remotely from the stimulation site, but coupled either directly to the stimulation lead(s) or indirectly to the stimulation lead(s) via a lead extension. The neurostimulation system may further include an external control device in the form of a remote control to remotely instruct the neurostimulator to generate electrical stimulation pulses in accordance with selected stimulation parameters.
Electrical stimulation energy may be delivered from the neurostimulator to the electrodes in the form of an electrical pulsed waveform. Thus, stimulation energy may be controllably delivered to the electrodes to stimulate neural tissue. The combination of electrodes used to deliver electrical pulses to the targeted tissue constitutes an electrode combination, with the electrodes capable of being selectively programmed to act as anodes (positive), cathodes (negative), or left off (zero). In other words, an electrode combination represents the polarity being positive, negative, or zero. Other parameters that may be controlled or varied include the amplitude, width, and rate of the electrical pulses provided through the electrode array. Each electrode combination, along with the electrical pulse parameters, can be referred to as a “stimulation parameter set.”
With some related art neurostimulation systems, and in particular, those with independently controlled current or voltage sources, the distribution of the current to the electrodes (including the case where the neurostimulator acts as an electrode) may be varied, such that the current is supplied via numerous different electrode configurations. However, the electrodes of different configurations may provide current or voltage in different relative percentages of positive and negative current or voltage to create different electrical current distributions (i.e., fractionalized electrode combinations).
As briefly discussed above, a remote control can be used to instruct the neurostimulator to generate electrical stimulation pulses in accordance with the selected stimulation parameters. Typically, the stimulation parameters programmed into the neurostimulator can be adjusted by manipulating controls on the remote control to modify the electrical stimulation provided by the neurostimulator system to the patient. Thus, in accordance with the stimulation parameters programmed by the remote control, electrical pulses can be delivered from the neurostimulator to the stimulation electrode(s) to stimulate or activate a volume of tissue in accordance with a set of stimulation parameters, and provide the desired efficacious therapy to the patient. The best stimulus parameter set will typically be one that delivers stimulation energy to the volume of tissue that must be stimulated in order to provide the therapeutic benefit (e.g., treatment of pain), while minimizing the volume of non-target tissue that is stimulated.
However, the number of electrodes that are available, combined with the ability to generate a variety of complex stimulation pulses, presents a huge selection of stimulation parameter sets to the clinician or patient. For example, if the neurostimulation system to be programmed has an array of sixteen electrodes, millions of stimulation parameter sets may be available for programming into the neurostimulation system. Today, neurostimulation systems may include up to thirty-two electrodes, thereby exponentially increasing the number of stimulation parameter sets available for programming.
To facilitate selection among the large number of potential stimulation parameter sets, clinicians generally program the neurostimulator through a computerized programming system. The programming system can be a self-contained hardware/software system, or can be defined predominantly by software running on a standard personal computer (PC). The PC or custom hardware may actively control the characteristics of the electrical stimulation generated by the neurostimulator to allow the optimum stimulation parameters to be determined based on patient feedback (or other data), and to subsequently program the neurostimulator and optionally the remote control, with the optimum stimulation parameter set(s).
The Bionic Navigator®, available from Boston Scientific Neuromodulation Corporation, Valencia, Calif., is a related art computerized programming system for SCS. The Bionic Navigator® is a software package that operates on a suitable PC, and allows clinicians to program stimulation parameters into an external handheld programmer (referred to as a remote control). Each set of stimulation parameters, including fractionalized current distribution to the electrodes (as percentage cathodic current, percentage anodic current, or off), may be stored in both the Bionic Navigator® and the remote control, and combined into a stimulation program that can then be used to stimulate multiple regions within the patient.
Prior to creating the stimulation programs, the Bionic Navigator® may be operated by a clinician in a “manual mode” to manually select the percentage cathodic current and percentage anodic current flowing through the electrodes, or may be operated by the clinician in an “automated mode” to electrically “steer” the current along the implanted leads in real-time using a directional input device as an integral part of the user interface (e.g., joystick, button pad, group of keyboard arrow keys, and/or similar or equivalent controls), thereby facilitating the clinician's attempts to determine preferable or the most efficacious stimulation parameter sets that can then be stored and eventually combined into stimulation programs. The steering depends on the type of leads, the number of leads, and the arrangement of the electrodes implanted. Once a polarity and the amplitude (either as an absolute or a percentage) for the current or voltage on an active electrode is selected in a typical computerized programming system, the polarity and amplitude value associated with the electrodes may be presented on a display screen so as to be viewable by the user.
Despite the fact that computerized programming systems have been used to speed up the programming process, programming electrical stimulation systems using present-day computerized programming systems are relatively time-consuming. In the automated or current steering mode, the clinician manipulates the directional input device in pre-defined increments to adjust a current stimulation field generated due to the realignment of the stimulation parameters, such as amplitude of the current associated with the electrodes, from one preset value to the next preset value. If the difference between the desired preset value and the existing preset value is large, then the number of manipulations of the input directional device may be high, which delays the process of selecting optimized stimulation parameter settings.
Also for the automated or current steering mode, the inherent limitation of directional input device restricts the user's ability to maneuver the device minutely or with complete freedom, and thus the user may fail to benefit from preferable or optimal stimulation settings.
There, thus, remains a need to provide a simplified and efficient directional current steering programming of the electrodes of neurostimulation system.